December 8, 2015 Subject:
To the uploader:
The derived files are botched. Objects moving horizontally in
the .ogv file have horribly jagged edges. Apparently, an
interlaced (telecined) video file was rescaled vertically without
being delaced while producing the derived files.
"SAR 1:1" means that the aspect-ratio of the pixels is 1:1.
I'm guessing that the orginial file had a picture size of
720x480 with pixels that weren't square. During the transcoding
to produce the .avi file, the picture was rescaled in order to
make the pixels square; in order to avoid the damage caused by
rescaling interlaced video, the odd and even lines were
separated, rescaled, and then recombined.
This resulted in a file that the Archive's automated deriving
process can't handle correctly.
My suggestion to the uploader would be this:
When producing the avi file, use a delacing (or pullup) filter, then
rescale the picture to 640x480. This seems to be what most
uploaders do on the Internet and in binary newsgroups.
The Happy Swordsman uploads interlaced (telecined) mpeg2 files
that have not been rescaled or delaced, and the Archive derives
good .ogv and .mp4 videos from them (perhaps because they are
mpeg2 and they have the standard dimensions 720x480).